The primary focus of these studies is to examine the nature of idiotype bearing T cell receptors, their expression, and their role in regulation of the immune response via the proposed idiotypic network. We plan to study these aspects using the well-defined unideterminant antigen L-tyrosine-p-azophenyl-trimethyl ammonium (tyr(TMA)) which in mice can induce cell mediated immunity in the absence of detectable antibody production. This proposal will focus primarily on T helper (Th), T suppressor (Ts), and antigen specific lymphocyte transformation which can be induced by tyr(TMA). Antibody to tyr(TMA) can be generated by protein-tyr (TMA) conjugates and is characterized by a major cross reactive idiotype (CRI-TMA). Idiotypic antisera made to these antibodies will be used to study the nature of the receptors, their expression, and their function on the three subpopulations of T lymphocytes. A major focus of the proposal will deal with the role of idiotypic restrictions between collaborating cell types reacting to the single determinant tyr(TMA). This will be approached by using both allotype congenic mice as well as idiotypically manipulated animals. The use of these mice will allow the study of regulatory interactions between cell types which differ only in their idiotypic make-up. Finally, the idiotypic antiserum will be used to isolate and characterize T cell receptor by serological and polyacrylamide gel analysis. The information from these studies should contribute information to the role of idiotype-bearing T and B cell receptors in the network theory of immune regulation.